Oops, I indicated that Integer.MAX_INT was 2^301, but it is 2^311 or 2,147,483,647. So the
largest document number in Lucene would be 2,147,483,646 and the largest number (count) of
documents would be 2,147,483,647.
 Jack Krupansky
From: Jack Krupansky
Sent: Sunday, June 03, 2012 4:09 PM
To: dev@lucene.apache.org
Subject: Re: What is the maximum document number?
The javadoc for IR.maxDoc refers to “largest possible document number”, but the word “possible”
is confusing. Superficially it sounds like the largest document number that Lucene can ever
assign, but really it is simply the “largest document number in the index at the moment,
including deleted documents.”
The javadoc should probably simply say: numDocs = maxDocs  numDeletedDocs
 Jack Krupansky
From: Uwe Schindler
Sent: Sunday, June 03, 2012 3:47 PM
To: dev@lucene.apache.org
Subject: Re: What is the maximum document number?
Hi,
In fact maxDoc is not the maximum, it is also a count. If no deletions are in an index, maxDoc==numDocs.
That's unfortunately how it is, maybe we should rename that in 4.0.
Uwe

Uwe Schindler
H.H.MeierAllee 63, 28213 Bremen
http://www.thetaphi.de
Jack Krupansky <jack@basetechnology.com> schrieb:
Doing a little more research on document numbers, I had thought that the maximum document
number was 2^301 or Integer.MAX_INT, but... I see that IndexReader.numDocs, maxDoc, and the
corresponding IndexWriter methods return the number of documents as an int, so since document
numbers start at zero, the number of documents is actually limited to 2^301, so the highest
document number is limited to 2^301 minus another 1 or 2^302.
 Jack Krupansky
